Has the external mic noise while charging issue been fixed on the SJ9 Strike?

Discussion in 'SJ9 Series' started by Oleg Gorfinkel, Jan 20, 2020.

  1. Oleg Gorfinkel

    Oleg Gorfinkel New Member

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    Hi everyone,

    I'd like to know if on the SJ9 SJCAM has fixed the issue that had been previously reported for the SJ8 series, whereby interference noise ruined the external mic recording when simultaneously charging with a custom adapter (see the thread: https://sjcam.com/community/threads/external-stereo-mic-adapter-for-sj8.2481/). This is very important to me, as I need this camera for recording long lectures, where the battery will not suffice, so continuous charging while recording is an ABSOLUTE requirement.

    Thanks!
     
  2. bokutouzawa

    bokutouzawa New Member

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    I was troubled about the noise when using the external power supply and external microphone of the SJ8 together, but I solved it by creating my own cable.
    Applying an external power supply voltage to the external microphone will eliminate the noise.
    Probably the same for SJ9.
    When I get home I will upload the schematic.
     
  3. Oleg Gorfinkel

    Oleg Gorfinkel New Member

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    Hey, that's great, I look forward to seeing the schematic! Maybe I shouldn't have sold my SJ8 Pro after all... Well, I guess, if this hack really solves the issue, I can buy it again, and it'll cost me even less than it did a year ago...

    I have a question, though: didn't you use a DIY cable when you first tried external mic recording and charging at the same time, BEFORE you discovered the voltage-to-mic hack? As far as I know, there is no official external mic adapter with a charge input...
     
  4. bokutouzawa

    bokutouzawa New Member

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    I do not use an official microphone adapter. I made my own using a general-purpose USB type-C connector.
    USB type-C connector is "GHW-L03" purchased on Aliexpress.

    It is a photograph of a circuit diagram and used parts. When this was attached to the SJ8 and an external power supply and external microphone were used at the same time, the noise was completely suppressed.

    Both resistors are 2.4KΩ and both capacitors are 1uF. There is no problem if similar values are not always required.
    The switches and the dotted diodes in the schematic are not necessary. This is to switch between the external microphone and the internal microphone while keeping the cable connected.
     

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    Last edited: Jan 24, 2020
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  5. bokutouzawa

    bokutouzawa New Member

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    When the switch connecting R and G on the front is shorted, an external microphone is used. When open, the internal microphone is used.
    If you only use an external microphone, connect it without the switch.

    The dashed diodes and switches from A2 and B11 on the back are for when using only an external microphone without using an external power supply.
    The dotted line is not required if you always supply external power when using an external microphone.
     
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  6. Oleg Gorfinkel

    Oleg Gorfinkel New Member

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    Wow, man, you are a genius. SJCAM would be a much better company if they had people like you working for them. As it is, they don't seem to care about fixing this very serious problem, even though they've known about it for years... Anyway, my first thought was to do this mod to the adapter I've already built and then buy the SJCAM again, but as I look at the sheer bulk of the components required, I'm having second thoughts. Might it be possible to find these components in micro size?
     
  7. nianeko2

    nianeko2 Member

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    Very interesting. Can you upload your recorded footage with the adapter?
     
  8. bokutouzawa

    bokutouzawa New Member

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    Hi, Gorfinkel,
    USB type-C adapters are sold from a single unit. However, it is better to buy more than one in case the processing fails.
    There is no link since it will be advertised, but please search on Aliexpress with the keyword "USB type-c connector". You can find the same connector I used.
    Capacitors and resistors are purchased in batches of 10 to 100 units, but they are very inexpensive.


    Hi, nianeko2,
    I discovered how to make this adapter a year ago, and I was looking forward to introducing it on my website, but I has been left untouched.
    I'm fun and crazy about mods that integrate digital cameras into old film cameras right now.
    Therefore, I can't afford to shoot SJCAM videos.sorry.
     

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    Last edited: Jan 24, 2020
  9. M3MOTO

    M3MOTO New Member

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    @bokutouzawa thank you for the schematic.
    Really big help to suppress humming noise.
    I am only using 1 electret mic can I just short A2 to B11 and use only 1 set of capacitor and resistor?

    Thank you
     

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